Blower apparatuses have been conventionally known and used in the art as a kind of work apparatuses used for blowing off fallen leaves on the ground or the like. A blower apparatus comprises a power-operated blower unit and an airflow tube (blowoff tube). The blower unit includes a drive motor, a volute casing, a fan rotatably supported within the volute casing and driven by the drive motor, and an airflow duct (a blow-out duct) connected to the volute casing for blowing out air impelled by the fan. The airflow tube is coupled to the airflow duct of the blower unit to blow out air from the open distal end of the airflow tube. In this type of blower apparatus, the air flowing out from the airflow duct passes through the airflow tube before it blows out from the open distal end, which is apt to cause generation of electrostatic charge on the volute casing and the airflow tube by the friction between air (including dust) and the inner circumferential walls of the volute casing and the airflow tube. Under these circumstances, when the user or operator of the blower apparatus holds the grip handle provided on the airflow tube, the electrostatic charge accumulated on the airflow tube would burst through to the hand of the operator, giving a harsh attack to the operator.
Various configurations have been conventionally proposed in the art to avoid unwanted attack of electrostatic discharge. An example of blower apparatuses with an arrangement provided within the blower tube for avoiding electrostatic discharge attack is disclosed in JP 2008-106660 A. The arrangement comprises a charge removing conductive wire provided within the airflow tube and having a free end positioned at the logitudinally intermediate point of the airflow tube and another end led outside the airflow tube through between the straight tube component and the elbow tube component of the airflow tube and electrically connected to the engine via an electrically conductive wire. The other end of the charge removing conductive wire which is connected to the electrically conductive wire is folded back toward the air to constitute a discharging wire. When this blower apparatus is in operation to blow out air from the airflow tube, the electrostatic charge generated on the inner wall of the airflow tube is gathered by the charge removing conductive wire violently streaming within the airflow tube and is discharged mostly to the engine and partly to the air.
Another example of blower apparatuses with an arrangement provided within the blower tube for avoiding electrostatic discharge attack is disclosed in U.S. Pat. No. 7,979,958 B2. The arrangement comprises a potential compensating conductor having a free end positioned centrally in the blower tube and another end connected to the drive motor, and an electrically conductive configuration from the potential compensating conductor and the drive motor to the ground device through the body of the operator, so that the charges on the potential compensating conductor and on the drive motor can be conducted away into the ground.
With the first example as mentioned above in which the electrostatic charge generated in the airflow tube is conducted away to the engine via the charge removing conductive wire, a potential difference may be established between the engine and the operator, and the electrostatic charge accumulated on the engine may flow through the throttle wire which is for controlling the throttle valve of the engine or through the lead wire which is for stopping the engine, and may attack the operator's hand holding the grip handle to which both the wires are extended from the engine. The operator should feel very uncomfortable.
With the second example as mentioned above in which the electrostatic charge on the potential compensating conductor and the engine is expected to be conducted away to the ground through the operator, it would be hard to thoroughly discharge the accumulated charge. Both of the above mentioned inconveniences would be obviated by hanging a conductive chain from the engine to reach the ground, but such an arrangement would cause another inconvenience for the operator to erroneously step on the chain during the operation.